If it is a loud intermittent clicking noise then I had the same thing with a new, but cheap, wheel that was only about 3 months old at the time. It seemed to be that the bearings were siezing up, I re greased the bearings but it didn't help for long.
In the end I rebuilt the wheel with a branded spare hub I had in stock.
Greasing bearings should be a fine job for a novice, just have a look at the instructional vids on YouTube. I wouldn't attempt wheel building until you are more experienced and confident. Unless you have very fancy wheels, it will probably be cheaper to replace than get a rebuild done.
Your current wheel might carry on running noisily for some time to come, the main danger is that it might seize up unexpectedly, or wear very rapidly and work loose.
Here's your homework for the weekend